Tooth decay is initiated by bacterial acids that destroy a region of the outer enamel layer of a tooth. This results in demineralization of the enamel sub-surface and surface leading to cavitation once the outer enamel layer is no longer structurally viable. At this point the tooth will require a filling. If this acid etching process reaches the underlying and more porous dentin, a more serious destruction occurs that could require extraction of the tooth and at best the tooth will require a more invasive filling. Typically at this point the cavity can be seen on X-ray and often by eye or by tactile probing with a dental explorer. However, if this demineralization process can be detected and monitored by optical imaging, then tooth decay may be managed, for example, by improving dental hygiene or pharmaceutically induced remineralization therapy.
X-ray and visual inspection often lacks the sensitivity to detect lesions at an early enough stage where remineralization is possible. In addition, repetitive monitoring of suspected demineralization by X-ray imaging may be not safe to use for children. Other detection means such as using ultrasound technologies may lack sufficient sensitivity and specificity, be bulky and expensive. Therefore, a need exists for a reliable, non-invasive and cost-effective means for identifying dental caries.